Electrosurgery unit and instrument

ABSTRACT

An electrosurgery unit for carrying out various medical or dental operations. An oscillator of the unit provides an output signal of a given high frequency, and this signal is received by a pre-amplifier which provides an amplified signal. An output amplifier receives the latter signal and provides a given output, while an output coupler connects the output of the output amplifier to a high-impedence load which in the case of dental surgery may be the gums which are treated. A power supply is provided for supplying voltage to the oscillator, pre-amplifier and output amplifier. For coagulating operations the unit provides a fully modulated high frequency signal. For cutting operations, the unit provides a ripple-free constant amplitude high frequency output. A selecting switch is provided for selecting between the operations.

United States Patent Hao et a1.

[54] ELECTROSURGERY UNIT AND INSTRUMENT Dec. 26, 1972 PrimaryExaminer-William E. Kamm [72] Inventors: Shya Hao, Monsey; Alvin M.Attorney-Stank? & Blake Chasen' Alan M. Miller, both of Spring valle allof N.Y. [57] ABSTRACT An electrosurgery unit for carrying out variousmedi- [73] A sslgnee' Majesco New York cal or dental operations. Anoscillator of the unit pro- [2 Flledl 06L 1970 vides an output signal ofa given high frequency, and 21 A L N 81 431 this signal is received by apre-amplifier which pro- 1 pp 0 vides an amplified signal. An outputamplifier receives the latter signal and provides a given output, whilean 5 128/303-19 output coupler connects the output ofthe output amlllt.Cl. to a highjmpedence load in the case of 0f sal'ch dental surgery maybe the gums are treated A 128/303-18 405, 411, power supply is providedfor supplying voltage to the 421i 422, 419 R, 415 oscillator,pre-amplifier and output amplifier. For

coagulating operations the unit provides a fully modu- [56] Rderencescued lated high frequency signal. For cutting operations, UNITED STATESPATENTS the unit provides a ripple-free constant amplitude highfrequency output. A selecting switch is provided for 2,993,178 7/1961Burger ..128l3 03.14 selecting between the operations. 2,949,107 8/1960Ziegler "HAS/303.13 3,054,405 9/ 1962 Tap er ..128/303.l8 10 Claims, 4Drawing Figures /0 /f Li 243 05014470,? pas-441 11059 H Oil/parA/WPUF/ER i ourpur COUPL ER! l M r l 1 7 i I i a I l .1 I l 1 I I l L 6222 rear Pan/m AEVEL:

T 5 7 H GOA IROQ POM EA SUPPL V ELECTROSURGERY UNIT AND INSTRUMENTBACKGROUND OF THE INVENTION of vacuum tubes with perhaps part of thecircuits including semiconductor diodes. This latter type of device isusually undesirably bulky and heavy. It generates an undesirablyexcessive amount of heat even when it is only in a standby condition.The filaments of the tubes require a given warm-up time, and the timerequired during the turn-on waiting period is generally longer than thevery short time required for the actual operations. The vacuum tubesunavoidably age, so that devices of this type generally require constantservicing.

With conventional devices of the latter type, the power oscillator onindicator, mounted on the front panel of the electrosurgery device, doesnot indicate positively whether the output current is available at theprobe tip. As a result there is a safety hazard for the nurse in theevent that she attempts to clean the tip, as by using a piece of gauze.

On the other hand, vacuum tubes are high-impedance devices. The outputpower thereof can be easily coupled through a probe and tip to the loadwhich is of high-impedance. Also, the output power can easily be variedsimply by adjusting the tube screen grid potential.

However, the large bulk and weight of these conventional devices, aswell as the constant servicing thereof, with the inconvenience simplyinvolved in the time for waiting for the device to become operative,creates considerable problems which up to the present time have not beensolved.

SUMMARY OF THE INVENTION It is accordingly a primary object of thepresent invention to provide a unit which will avoid the abovedrawbacks.

Thus, it is an object of the invention to provide an electrosurgery unitwhich is extremely small and extremely light.

It is also an object of the invention to provide an electrosurgery unitwhich will generate heat only during operation, with the heat which isgenerated during standby being negligible.

It is also an object of the present invention to provide anelectrosurgery unit which is capable of achieving for cutting operationsa constant amplitude signal, commonly referred to as a fully rectifiedcurrent.

Also, it is an object of the invention to provide an electrosurgery unitwhich can provide a fully modulated signal, commonly referred to asunrectified current, for coagulating purposes.

It is also an object of the present invention to provide a unit of thistype which eliminates all effects of aging, so that servicing due toaging is eliminated.

Furthermore, it is an object of the invention to provide for use with aunit of this type or with other units, an instrument having a probecapableg of giving a positive indication that high frequency power ispresent at the probe tip.

Also it is an object of the present invention to provide an instrumentof this latter type which will greatly reduce the possibility of radiofrequency interference,

so that other electrical units used in the vicinity of the unit of theinvention will not be undesirably. influenced.

According to the invention the electrosurgery unit includes anoscillator means for providing of signal of given high frequency output.A pre-amplifier means is connected with the oscillator means forproviding an amplifier signal, and an output amplifier means receivesthe latter amplified signal to provide an output therefrom. An outputcoupler means receives the output from the output amplifier means andcouples the output to the high-impedance load which may be the gums inthe case of dental operations. A power supply means is provided forsupplying voltage to the oscillator means, the pre-amplifier means, andthe output amplifier means. A selecting means is connected with thepower supply means for selecting between an operation where the cuttingcircuit means is operative, for cutting operations, or where the cuttingcircuit means does not enter into the operation, so that coagulatingoperations can be carried out. The output coupler means includes acoaxial cable of predetermined length connected at one end to a probewhich removably carries a probe tip. Within the probe there is visible aneon lamp one lead of which is connected to the probe and the other leadof which has a capacitive relation with respect to the coaxial cable.The neon lamp glows when the voltage at the tip exceeds the breakdownvoltage of the bulb.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way ofexample in the accompanying drawings which form part of this applicationand in which:

FIG. 1 is a wiring diagram illustrating the circuitry of theelectrosurgery unit of the invention;

FIG. 2 is an enlarged sectional illustration of the probe showing thestructure in a plane which contains the longitudinal central axis of theprobe;

FIG. 3 is a side view of the electrosurgery unit; and

FIG. 4 is a plan view taken along line 44 of FIG. 3 in the direction ofthe arrows and showing the operating panel of the electrosurgery unit.

DESCRIPTION OF PREFERRED EMBODIMENTS Basically the device of the presentinvention forms an electrosurgery unit which is in the form of a highfrequency power oscillator having an output power applied to the patientat the part which is to be treated. For example, in the case of dentalsurgery the output power is applied to the patients gums through a probeand a tip. However, the electrosurgery unit can be used for generalmedical purposes such as in dermatology to remove various growths at theskin, and for many other medical purposes. A power level control isprovided in order to vary the output power to the required amount. Alsowith the instrument of the invention there is an indicator lamp whicheither is turned on or which glows brighter in intensity when the highfrequency power oscillator is turned on.

The oscillator is capable of achieving a coagulating current and acutting current. The coagulating current is characterized by alternatingsurging peaks of energy similar to an amplitude modulated signal withfull one hundred percent modulation. This current is used to stopbleeding such as bleeding of the gums. The cutting current ischaracterized by a constant amplitude signal achieving a constant flowcurrent used for cutting or removing small amounts of flesh, or smallamounts of gums in the case of dental surgery.

Referring now to FIG. 1, it will be seen that the electrosurgery unit ofthe invention includes an oscillator means 10, pre-amplifler means 12,an output amplifier means 14, an output coupler means 16, a power supplymeans 18 and a power-level control means 20.

The oscillator means is adapted to be turned on or off by actuation of afoot switch 22 of conventional construction. The circuit includescomponents such as the capacitor 24, the Zener diode 26, and theresistors 28 and 30 as well as the inductance coil 32, resistor 34, andcapacitors 36, 38 and 40, all of which are used to achievethe properimpedance matching for the circuitry. However, one of the importantfeatures of the oscillator circuit is that it includes a crystal 40which will achieve a constant frequency signal which is received bythepre-amplifier means 12.

This output signal is received at the base of the preamplifiertransistor 44. The pie-amplifier includes the variable capacitance 46 aswell as the inductance coil 48, the resistor 50, the capacitor 52 andthe inductance coil 54. The pre-amplifier means 12 amplifies the highfrequency signal received from the oscillator means 10. The amplifiedsignal is fed from the pre-amplifier means to the output amplifier means14 where it is received at the base of the transistor 56. The outputamplifier means includes the various capacitances, inductance coils andresistors illustrated so as to have proper impedance matching.

A further important feature of the invention resides in the power-levelcontrol means 20. The pre-arnplifier transistor 44 is a class Camplifier. The output of a class C amplifier is proportional to thesquare of the collector supply voltage. In order to vary the gain of aclass C amplifier it is conventional to connect a potentiometer betweenthe supply voltage and the collector of the transistor so that thecollector voltage or the amplifier gain can be varied. The result isthat a large amount of DC supply power will be dissipated in thepotentiometer. A potentiometer of high power dissipation is thereforerequired for gain control. It is unavoidable, therefore, that with thistype of construction a physically large control will be essential andthere will be a decrease in the efficiency of the entire design.

in contrast, with the present invention the powerlevel control meansincludes the transistor 58, connected into the circuit as a diode, thecapacitor 60, and the potentiometer 62. These latter componentsconnected into the circuit as illustrated in FIG. 1 constitute thepower-level control circuit means. The circuit is an amplitude detector.It converts a portion of the highfrequency signal at the base oftransistor 44 into direct current power. This converted DC power is thendissipated in the potentiometer 62. The amount of signal power which isdissipated depends upon the setting of the potentiometer 62. The morepower is dissipated in the potentiometer 62, the less the signal poweris amplified by the amplifier means 12 and 14. As a result, the outputpower of the unit depends on the setting of the potentiometer 62.

The output coupler means 16 receives the output from the transistor 56of the output amplifier means 14. The output transistor 56 requires avery low impedance on the order of a few ohms depending upon the maximumoutput power and power supply DC voltage. The impedance of the load,such as the gums in the mouth, has an impedance level on the order of afew thousand ohms. A special coupling network that transforms the outputload impedance into the desired collector impedence is required, so thatthe power generated by the transistor can be effectively transferred tothe load. Since the power oscillator operates at a high frequency, atuned coupling network is required.

Another requirement of the output coupler means 16 is that the outputpower be connected from the power oscillator by a flexible cable in theform of the-coaxial cable 64. This flexible cable is of a few feet inlength and is connected to a probe 66 which in turn removably carriesthrough a suitable chuck a probe tip 68, so that one tip can beexchanged for another as required. The cable 64 has a characteristicimpedance of 50 ohms. It is not terminated at the probe end. Since theprobe length is less than one-quarter of the wave length of the outputpower signal, the impedance looking into the cable end 70 is capacitive.This capacitor together with the capacitors 72 and 74 in seriesconstitute the output tuning capacitor of the output coupler network.Other components in the network are the illustrated inductor coil andgrounded cable shields.

As may be seen from FIG. 2, the coaxial cable 64 extends into thetubular housing 76 of the probe 66. This tubular housing has atransparent tubular wallportion 78 so that a glowing neon lamp 81 willbe visible therethrough.

The coaxial cable 64 includes an inner conductor embedded in andsurrounded by a suitable dielectric 82. This dielectric 82 is in turnsituated within and surrounded by a tubular metallic shield 84 which inturn is covered by the insulation 86. The inner conductor 80 of thecoaxial cable 64 is electrically connected directly with the probe 88provided with any suitable chuck 90 for removably connecting to theprobe the operating tip 92. Thus, one operating tip may be exchanged foranother. The neon lamp 8]. has one lead 94 connected electrically withthe lead 80; directly to the probe 88. The other lead 96 of the neonlamp, however, is not connected to any element. it simply rests withinthe tubular housing 76 at the region of the exterior of the coaxialcable 64 so as to have a capacitive relationship with respect to theshield which is surrounded by the insulation. Thus, this lamp 81 willindicate positively whether high frequency power is present at the tip92 and therefore forms a means for indicating the presence of highfrequency power at the tip. The small capacitance between the lead 96and the cable shield provides the ground return and also limits themaximum current passing through the neon lamp 81. This neon lamp glowswhen the voltage at the tip exceeds the breakdown voltage of the lamp.

it is to be noted that the coaxial cable 64 has at its end distant fromthe probe assembly 66 a prong capable of being received in any suitablereceptacle so that the coaxial cable together with the probe and otherdetails of FIG. 2 form a separate instrument which can be used withother suitable sources of energy for general medical, dental, and otherlike purposes.

The power supply means 18 includes the plug 100 which can be insertedinto any wall outlet receptacle for receiving the line voltage. Anon-off switch 102 is provided. The line voltage is delivered to atransformer 104 which converts the line voltage into a lower voltagerectified by the bridge rectifier 106. The power from the power supplymeans 18 is delivered through a conductor 108 to the output amplifiermeans 14. The power supply means further includes a cutting circuitformed primarily by the large electrolytic filtering capacitor 110, anda diode 112.

For coagulating operations the power supply means 18 will provide acollector supply tothe output transistor 56 which has the wave shape ofa fully rectified sine wave. This supply voltage modulates theoscillator signal so that the output signal takes the form of a 100percent modulated signal with alternating peaks of power occurring attwice the line frequency. For selecting this latter type of operation aselecting means is provided in the form of a selecting switch 1 14 whichcan be displaced by the operator to the coagulating position in which itis illustrated in FIG. 1. When the switch 114 is in the cut position thediode 112 is shorted and the line ripple is filtered out by the largeelectrolytic capacitor 110. As a result the supply voltage for theoscillator, pre-amplifier, as well as the output amplifier is lineripple free and the high frequency output has a constant amplitude. Whenthe switch 114 is set to the coagulating position, the diode 112prevents the line ripple from being filtered by the capacitor 110, withthe result that the above fully modulated signal is achieved.

The above-described circuitry, with the exception of the coaxial cableand probe connected thereto can be housed within a suitable housing such'as the housing 116 illustrated in side elevation in FIG. 3. All of theabove fully transistorized circuitry is enclosed within the housing 116with the cable which is connected to the plug 100 extending from thehousing so that the plug 100 can be connected with a suitable walloutlet or the like.

The housing 116 has at its front upper portion an inclined panel 118carrying a rotary knob 120 which forms the adjusting element for thepotentiometer 62. Referring to FIG. 4, the panel 118 is illustratedtherein. The knob 120 coacts with a suitable scale for indicating theadjustment of the potentiometer 62. Available at the panel 118 is alsothe on-off switch 102. Also the selecting switch 114 capable of beingplaced either in the cut or in the coagulating position is illustrated.The foot control switch 22 can be removably connected with a receptacle124. There is also an-lND receptacle 126 for receiving a conductorengaged by the patient for forming a ground connection with the patient.The end of the coaxial cable 64 distant from the probe 66 terminates ina prong which can be received in the receptacle 128.

Thus, with a conductor from receptacle 126 properly engaging thepatient, with a foot-control switch connected to the receptacle 124, andwith the probe 66 of the invention connected to the receptacle 128, itis possible, when the plug 100 is connected to a suitable source, toturn the switch 102 into the on position for starting the operation, andthere is virtually no waiting period required for warm-up purposes.Depending upon whether cut or coagulating operations are to be carriedout the switch 114 will be placed in one or the other of the positionsapparent from FIG. 4.

It is apparent from the above description and the drawings that thefully transistorized electrosurgery unit of the invention overcomes allof the drawbacks of the vacuum-tube type of structure. With thestructure of the invention the entire unit can be made quite small andof an exceedingly light weight. The only heat which is generated isgenerated during the actual operation. Any heat generated during standbyis negligible. There is achieved with the circuitry of the invention aproper constant amplitude signal for cutting operations. Also it ispossible to achieve for coagulating operations a fully modulated signal,commonly referred to as unrectified current. With the structure of theinvention servicing due to aging of the components is completelyeliminated. Furthermore, by way of the neon lamp there is a positiveindication that high frequency power is present at the probe tip.

What is claimed is:

1. In an electrosurgery unit, oscillator means for providing an outputof a given frequency, pre-amplifier means receiving said output fromsaid oscillator means and providing an amplified signal therefrom,output amplifier means receiving said signal from said pre-amplifiermeans and providing therefrom a predetermined output, output couplermeans receiving said output from said output amplifier means forcoupling the latter output to a high-impedance load, power supply meanselectrically connected with said oscillator means and pre-amplifiermeans for supplying at all times a constant amplitude output thereto,said power supply means normally providing for coagulating operations asupply voltage in the form of a fully rectified sine wave to said outputamplifier means, cutting circuit means electrically connected with saidpower supply means for coacting therewith to provide an output ofconstant amplitude, and selecting means coacting with said power supplymeans and cutting circuit means for selectively operating said powersupply means either without said cutting circuit means for coagulatingoperations or with said cutting circuit means for cutting operations,said oscillator means, pre-amplifier means, and output amplifier meansbeing fully transistorized.

2. The combination of claim 1 and wherein said oscillator means includesa crystal for providing a stable high-frequency output signal therefrom.

3. The combination of claim 1 and wherein a powerlevel control means isconnected with the input of said pre-amplifier means for acting on theoutput from said oscillator means for converting a portion of the signaltherefrom into direct current power and for then dissipating the latterpower.

4. The combination of claim 1 and wherein a foot switch is operativelyconnected with said oscillator circuit means for turning the latter onand off.

5. The combination of claim 1 and wherein said output coupler meansincludes a coaxial cable of predetermined length and a probe connectedelectrically thereto and terminating in an operating tip, and a neonlamp connected electrically with the probe and having a capacitiverelation with respect to said coaxial cable for glowing when the voltageat the probe tip exceeds the breakdown voltage of said lamp.

6. The combination of claim and wherein said probe includes a selectedoperating tip and a chuck removably connecting said selected operatingtip thereto, so that one operating tip may be exchanged for another.

7. in an electrosurgery unit, oscillator means for providing an outputof a given frequency, pre-amplifier means receiving said output fromsaid oscillator means and providing an amplified signal therefrom,output amplifier means receiving said signal from said pre-amplifiermeans and providing therefrom a predetermined output, output couplermeans receiving said output from said output amplifier means forcoupling the latter output to a high-impedance load, power supply meanselectrically connected with said oscillator means, preamplifier meansand output amplifier means for supplying a voltage thereto, cuttingcircuit means electrically connected with said power supply means, andselecting means coacting with said power supply means and cuttingcircuit means for selectively operating said power supply means eitherwithout said cutting circuit means for coagulating operations or withsaid cutting circuit means for cutting operations, said oscillatormeans, pre-amplifier means, and output amplifier means being fullytransistorized, a power-level control means connected with the input ofsaid pre-amplifier means for acting on the output from said oscillatormeans for converting a portion of the signal therefrom into directcurrent power and for then dissipating the latter power, saidpower-level control means including a transistor connected as a diode, acapacitor, and a potentiometer, said capacitor and potentiometer beingelectrically connected in parallel with each other and in series withthe transistor between ground and the input of said pre-amplifier means,and said transistor and capacitor converting the signal from saidoscillator means into direct current power and said potentiometerdissipating the direct current power, with the extent of signal powerdissipation being determined by the setting of said potentiometer.

8. in an electrosurgery unit, oscillator means for providing an outputof a given frequency, pre-amplifier means receiving said output fromsaid oscillator means and providing an amplified signal therefrom,output amplifier means receiving said signal from said pre-amplifiermeans and providing therefrom a predetermined output, output couplermeans receiving said output from said output amplifier means forcoupling the latter output to a high-impedance load, power supply meanselectrically connected with said oscillator means, preamplifier meansand output amplifier means for supplying a voltage thereto, cuttingcircuit means electrically connected with said power supply means, andselecting means coacting with said power supply means and cuttingcircuit means for selectively operating said power supply means eitherwithout said cutting circuit means for coagulating operations or withsaid cutting circuit means for cutting operations, said oscillatormeans, pre-amplifier means, and output amplifier means being fullytransistorized, said cutting circuit means including a filteringcapacitor and a diode connected between the latter capacitor and saidpower supply means for preventing filtering by said filtering capacitor,said selecting means bridging said diode when set for cutting operationsto render said filtering capacitor operative.

In an electrosurgery unit, oscillator means for providing an output of agiven frequency, pre-amplifier means receiving said output from saidoscillator means and providing an amplified signal therefrom, outputamplifier means receiving said signal from said pre-amplifier means andproviding therefrom a predetermined output, output coupler meansreceiving said output from said output amplifier means for coupling thelatter output to a high-impedance load, power supply means electricallyconnected with said oscillator means, preamplifier means and outputamplifier means for supplying a voltage thereto, cutting circuit meanselectrically connected with said power supply means, and selecting meanscoacting with said power supply means and cutting circuit means forselectively operating said power supply means either without saidcutting circuit means for coagulating operations or with said cuttingcircuit means for cutting operations, said oscillator means,pre-amplifier means, and output amplifier means being fullytransistorized, said output coupler means including a coaxial cable ofpredetermined length and a probe connected electrically thereto andterminating in an operating tip, and a neon lamp connected electricallywith the probe and having a capacitive relation with respect to saidcoaxial cable for glowing when the voltage at the probe tip exceeds thebreakdown voltage of said lamp, said coaxial cable including an innerconductor, a dielectric surrounding said conductor, and a shieldsurrounding said dielectric and covered by insulation, said neon lamphaving one lead connected to said probe and another lead terminating inthe region of said shield for providing the capacitive relationshiptherewith.

10. An instrument for carrying out electrosurgical operations,comprising an elongated coaxial cable having at one end a means forconnecting the cable to a suitable source, a probe electricallyconnected with the opposite end of said cable, said probe carrying anoperating tip, and a neon lamp carried by said probe for providing avisible signal when said lamp glows, said lamp being electricallyconnected with said probe and having a capacitive relationship withrespect to said cable for glowing when the voltage at said tip exceedsthe breakdown voltage of said lamp, said coaxial cable including aninner conductor, a dielectric surrounding the latter conductor, a shieldsurrounding the dielectric and insulation surrounding the shield, saidconductor being electrically connected with said probe and one lead ofsaid neon lamp also being electrically connected with said probe, theother lead of said neon lamp being situated in the vicinity of saidshield to have a capacitive relationship therewith.

1. In an electrosurgery unit, oscillator means for providing an outputof a given frequency, pre-amplifier means receiving said output fromsaid oscillator means and providing an amplified signal therefrom,output amplifier means receiving said signal from said pre-amplifiermeans and providing therefrom a predetermined output, output couplermeans receiving said output from said output amplifier means forcoupling the latter output to a high-impedance load, power supply meanselectrically connected with said oscillator means and pre-amplifiermeans for supplying at all times a constant amplitude output thereto,said power supply means normally providing for coagUlating operations asupply voltage in the form of a fully rectified sine wave to said outputamplifier means, cutting circuit means electrically connected with saidpower supply means for coacting therewith to provide an output ofconstant amplitude, and selecting means coacting with said power supplymeans and cutting circuit means for selectively operating said powersupply means either without said cutting circuit means for coagulatingoperations or with said cutting circuit means for cutting operations,said oscillator means, pre-amplifier means, and output amplifier meansbeing fully transistorized.
 2. The combination of claim 1 and whereinsaid oscillator means includes a crystal for providing a stablehigh-frequency output signal therefrom.
 3. The combination of claim 1and wherein a power-level control means is connected with the input ofsaid pre-amplifier means for acting on the output from said oscillatormeans for converting a portion of the signal therefrom into directcurrent power and for then dissipating the latter power.
 4. Thecombination of claim 1 and wherein a foot switch is operativelyconnected with said oscillator circuit means for turning the latter onand off.
 5. The combination of claim 1 and wherein said output couplermeans includes a coaxial cable of predetermined length and a probeconnected electrically thereto and terminating in an operating tip, anda neon lamp connected electrically with the probe and having acapacitive relation with respect to said coaxial cable for glowing whenthe voltage at the probe tip exceeds the breakdown voltage of said lamp.6. The combination of claim 5 and wherein said probe includes a selectedoperating tip and a chuck removably connecting said selected operatingtip thereto, so that one operating tip may be exchanged for another. 7.In an electrosurgery unit, oscillator means for providing an output of agiven frequency, pre-amplifier means receiving said output from saidoscillator means and providing an amplified signal therefrom, outputamplifier means receiving said signal from said pre-amplifier means andproviding therefrom a predetermined output, output coupler meansreceiving said output from said output amplifier means for coupling thelatter output to a high-impedance load, power supply means electricallyconnected with said oscillator means, pre-amplifier means and outputamplifier means for supplying a voltage thereto, cutting circuit meanselectrically connected with said power supply means, and selecting meanscoacting with said power supply means and cutting circuit means forselectively operating said power supply means either without saidcutting circuit means for coagulating operations or with said cuttingcircuit means for cutting operations, said oscillator means,pre-amplifier means, and output amplifier means being fullytransistorized, a power-level control means connected with the input ofsaid pre-amplifier means for acting on the output from said oscillatormeans for converting a portion of the signal therefrom into directcurrent power and for then dissipating the latter power, saidpower-level control means including a transistor connected as a diode, acapacitor, and a potentiometer, said capacitor and potentiometer beingelectrically connected in parallel with each other and in series withthe transistor between ground and the input of said pre-amplifier means,and said transistor and capacitor converting the signal from saidoscillator means into direct current power and said potentiometerdissipating the direct current power, with the extent of signal powerdissipation being determined by the setting of said potentiometer.
 8. Inan electrosurgery unit, oscillator means for providing an output of agiven frequency, pre-amplifier means receiving said output from saidoscillator means and providing an amplified signal therefrom, outputamplifier means receiving said signal from said pre-amplifier means andproviding therefrom a predetermined outPut, output coupler meansreceiving said output from said output amplifier means for coupling thelatter output to a high-impedance load, power supply means electricallyconnected with said oscillator means, pre-amplifier means and outputamplifier means for supplying a voltage thereto, cutting circuit meanselectrically connected with said power supply means, and selecting meanscoacting with said power supply means and cutting circuit means forselectively operating said power supply means either without saidcutting circuit means for coagulating operations or with said cuttingcircuit means for cutting operations, said oscillator means,pre-amplifier means, and output amplifier means being fullytransistorized, said cutting circuit means including a filteringcapacitor and a diode connected between the latter capacitor and saidpower supply means for preventing filtering by said filtering capacitor,said selecting means bridging said diode when set for cutting operationsto render said filtering capacitor operative.
 9. In an electrosurgeryunit, oscillator means for providing an output of a given frequency,pre-amplifier means receiving said output from said oscillator means andproviding an amplified signal therefrom, output amplifier meansreceiving said signal from said pre-amplifier means and providingtherefrom a predetermined output, output coupler means receiving saidoutput from said output amplifier means for coupling the latter outputto a high-impedance load, power supply means electrically connected withsaid oscillator means, pre-amplifier means and output amplifier meansfor supplying a voltage thereto, cutting circuit means electricallyconnected with said power supply means, and selecting means coactingwith said power supply means and cutting circuit means for selectivelyoperating said power supply means either without said cutting circuitmeans for coagulating operations or with said cutting circuit means forcutting operations, said oscillator means, pre-amplifier means, andoutput amplifier means being fully transistorized, said output couplermeans including a coaxial cable of predetermined length and a probeconnected electrically thereto and terminating in an operating tip, anda neon lamp connected electrically with the probe and having acapacitive relation with respect to said coaxial cable for glowing whenthe voltage at the probe tip exceeds the breakdown voltage of said lamp,said coaxial cable including an inner conductor, a dielectricsurrounding said conductor, and a shield surrounding said dielectric andcovered by insulation, said neon lamp having one lead connected to saidprobe and another lead terminating in the region of said shield forproviding the capacitive relationship therewith.
 10. An instrument forcarrying out electrosurgical operations, comprising an elongated coaxialcable having at one end a means for connecting the cable to a suitablesource, a probe electrically connected with the opposite end of saidcable, said probe carrying an operating tip, and a neon lamp carried bysaid probe for providing a visible signal when said lamp glows, saidlamp being electrically connected with said probe and having acapacitive relationship with respect to said cable for glowing when thevoltage at said tip exceeds the breakdown voltage of said lamp, saidcoaxial cable including an inner conductor, a dielectric surrounding thelatter conductor, a shield surrounding the dielectric and insulationsurrounding the shield, said conductor being electrically connected withsaid probe and one lead of said neon lamp also being electricallyconnected with said probe, the other lead of said neon lamp beingsituated in the vicinity of said shield to have a capacitiverelationship therewith.